The low overtone QNMs of Schwarzschild-AdS black holes for scalar perturbations were first calculated numerically by Horowitz and Hubeny [1]}. They computed these modes in four, five, and seven spacetime dimensions, which are of interest in the context of the AdS/CFT correspondence. This work was completed by Zhu et al. [2]} and Konoplya [3]}, who analyzed the scalar QNMs for small Schwarzschild-AdS black holes in detail. Cardoso and Lemos [4]} extended these calculations to include electromagnetic and gravitational perturbations. In addition, Moss and Norman [5]} calculated roughly twenty QNM roots for the gravitational perturbations of the Schwarzschild-AdS black hole and showed the duality between axial and polar perturbations can be preserved if we apply Dirichlet boundary conditions to axial perturbations, and Robin boundary conditions to polar perturbations. Berti and Kokkotas confirmed all the above results in [6]} and extended their numerical calculations to Reissner-Nordström black holes in AdS spacetime. Finally, the low overtone QNMs of Dirac spinors are addressed by Giammatteo and Jing in [7]}. Motivated by AdS/CFT correspondence, many authors have extended the QNM calculations to higher spacetime dimensions (some examples are given in [8]}). All these authors used either the method developed by Horowitz and Hubeny [1]} or some variation of the Fröbenius method. As far as we know, no one has applied Leaver's continued fraction method [10]} to calculate the QNMs of Schwarzschild-AdS black holes. The continued fraction method has proven to be the most reliable numerical technique to calculate these modes. Also, the continued fraction method with Nollert's improvement [11]} is able to extend the numerical calculations to high overtone modes with very good precision.
